The present invention relates to an electronic lock.
Electronic locks have many advantages over mechanical locks. For example, electronic locks used in combination with a microprocessor or a computer can be programed to control the electronic lock by time of day, by authorization codes, or other factors that may be programed into the processor. When a key is lost, instead of replacing the electronic lock, the electronic lock may be reprogrammed to accept a different identification code from a different key.
However, electronic locks suffer from a number of drawbacks. First, the locks require a source of power. If the power source is provided within the lock, such as in the form of a battery, then the power supply occupies space within the lock, making the lock larger. Such batteries may also be prone to corrosion which can affect the internal parts of the lock. In addition, if the battery loses power, then the lock may no longer be able to function. Further, the lock must be accessed periodically in order to change the battery. Providing power from a standard electrical power line is an alternative, but requires providing wiring to the lock. Further, such wiring may not be available in some environments, such as a desk or cabinet.
It is also desired to make the locks as small as possible, so that the electronic lock may be installed in place of an existing mechanical lock. Conventional mechanical locks used with desks or cabinets are relatively small. Thus, the space available within such a lock is confined, limiting the size and number of components that may be used within a lock.
Another difficulty with electronic locks is that they are susceptible to opening in response to sharp blows. Typically, electronic locks use a solenoid. However, it is often possible to jar a solenoid plunger so that an electronic lock may be opened by applying a sharp force to the lock, such as striking a lock with a hammer.
Another problem with electronic locks is that often a solenoid is used to move a plunger into and out of interfering relationship with the internal cylinder and the external shell. This may result in several problems. First, the solenoid and its plunger must be constructed to withstand the primary force directed on the plunger when a person attempts to rotate the cylinder when locked. Another problem is that the electronic lock may be difficult to lock, since it may be difficult to align the plunger with its corresponding bore. If the plunger does not align properly with the bore, the plunger cannot enter the bore so as to interfere with the movement of the cylinder.
Yet another problem is that some electronic locks allow removal of the key during rotation of the lock. In that event, a person may forget to return the cylinder to its locked position after the lock has been opened.
Accordingly, what is therefore desired is an electronic lock that occupies a small volume, may be used to replace existing mechanical locks, that does not require a power source inside of the lock or external wiring, that is not susceptible to being opened in response to tampering, that may be consistently returned to a position that allows secure locking, and that prevents withdrawal of a key during operation.
The present invention provides an electronic locking system that overcomes the aforesaid drawbacks of the prior art. In a first separate aspect of the invention, an electronic locking system comprises a cylinder housed within and rotatable with respect to a shell. A key has a power supply. At least one of the cylinder and key is capable of generating a signal when the key is engaged with the cylinder. An electrically powered locking mechanism is housed entirely within the cylinder and includes a lock member movable between an open position inside the cylinder and a locked position. The lock member in the locked position interferes with movement of the cylinder. The power supply is electrically connected to the locking mechanism. The locking mechanism allows movement of the lock member from the locked position to the open position in response to the signal, so that the cylinder may be rotated within the shell. All of the components of the locking mechanism are housed within the cylinder when the cylinder is rotated. Thus, this aspect of the invention has the advantages of providing a small lock that may be used to replace existing mechanical locks, and that does not require a power supply in the lock or external wiring to provide power.
In another separate aspect of the invention, an electronic locking system comprises a cylinder housed within and rotatable with respect to a shell. At least one of a key and the cylinder is capable of generating a signal when the key is engaged with the cylinder. An electrically powered locking mechanism in the cylinder includes a lock member that is moveable between an open position and a locked position. The lock member in the locked position interferes with movement of the cylinder. The locking mechanism further includes an interfering member moveable between an interfering position and a non-interfering position. The interfering member in the interfering position resists movement of the lock member, and the interfering member in the non-interfering position allows movement of the lock member. The locking mechanism moves the interfering member from the interfering position to the non-interfering position in response to the signal so that the cylinder may be rotated within the shell. This aspect of the invention has the advantage of using a two part system so that the lock member may be designed to withstand large primary forces, while the interfering member, which may be a solenoid, is not subjected to large direct forces.
In a third separate aspect of the invention, an electronic locking system comprises a cylinder housed within and rotatable with respect to the shell. At least one of a key and the cylinder is capable of generating a signal when the key is engaged with the cylinder. An electrically powered locking mechanism includes a lock member that is moveable between an open position and a locked position. The locking mechanism allows movement of the locking member from the locked to the open position in response to receiving the signal so that the cylinder may be rotated within the shell. A biasing mechanism urges the cylinder toward a home position when the cylinder is rotated away from the home position. This aspect of the invention has the advantage of aligning the cylinder to a position that will allow the lock to be secured.
Preferably, the electronic locking systems described above further include an anti-tamper mechanism to prevent the lock from being opened as a result of a sharp blow to the lock. In addition, the locking systems preferably further include a key retention mechanism that prevents the key from being disengaged from the lock when the cylinder is rotated away from the home position.
In addition to the advantages described above, the various aspects of the invention may each provide one or more of the following advantages. By housing the operative components of the locking mechanism entirely within the cylinder, a locking system may be manufactured to fit within a very small volume. Thus, the electronic lock may be used to replace conventional mechanical cylinder locks. In addition, in the event an installed lock fails, the cylinder may be replaced without replacing the entire lock. The present invention also does not require the use of a power supply within the lock itself. Thus, the lock can be smaller because it does not contain a power supply, and is not susceptible to corrosion resulting from a corroding battery. Nor does the lock require an external source of power from external wiring. The lock is thus simpler and easier to install.
The foregoing and other features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.